A. Field of the Invention
This invention relates generally to trailer having a crane type hoisting structure, and more particularly to such a trailer wherein the crane mast is rotatably mounted with braking mechanism regulating mast rotation.
B. Description of the Prior Art
Grave headstones generally are sufficiently massive to make their handling and transport relative difficult and often not possible by workmen without mechanical assistance. The handling of headstones is a common requirement about cemeteries, but notwithstanding, few mechanisms have been designed specifically for this purpose.
Headstone handling commonly has been accomplished by use of existing vehicles found about a cemetery, usually a backhoe, with or without the assistance of some secondary transport vehicle. Some headstone handling has been accomplished by concrete vault moving devices such as that disclosed in U.S. Pat. No. 2,915,206. In either case, however, the handling operation generally has required at least two workmen for its accomplishment, though neither workman is fully involved during the handling process for the entire period to make the operation inefficient. My invention solves this problem by providing a novel vehicle with a crane specifically adapted to the handling and transport of grave headstones by a single workman.
Vehicles having pivotally or rotatably mounted crane structures have heretofore become known for various purposes, though apparently not specifically for gravestone placement. Such vehicles generally have been of a self-powered nature rather than in the form of a trailer that is releasably attached to some secondary vehicle for transport. Since a vehicle for grave headstone placement is fairly specialized and not continuously usable in most cemeteries, my trailer type vehicle with its substantially lower cost than a self-propelled vehicle is more economically feasible and is distinguished in this regard over the self-propelled type vehicles.
The crane carrying vehicles that have pivotally or rotatably mounted a crane mast that is not powered for rotation generally have provided a freely movable mast that is not restrainable from pivoting motion in any adjustable fashion. This type of device may be used for placement of headstones on level grounds by a single workman, as in such circumstance the workman generally may manually move a hoisted headstone in a horizontal plane and have it remain in position while he moves away to control at a distance on the vehicle to raise or lower the stone. This operation, however, is not possible for a single workman loading or placing headstones with a vehicle on a sloping surface, as a freely rotatable mast will rotate to a position where the suspended headstone is at its lowest point.
My invention is distinguished from this type of device by providing a braking mechanism between the mast and its support structure that allows selectively adjustable friction between the two elements to allow a single workman to adjust the rotary position of a suspended headstone from a control point on the trailer spacedly distant from the headstone. This type of interconnecting structure provides an additional aid to the workman as the vehicle may be placed on the upper side of a sloping site where a stone is to be placed and the braking linkage used to allow gravity to rotate the crane mast to an appropriate position whereunder the headstone is to be placed. Similarly in loading headstones on a sloping surface, the vehicle may be positioned on the downhill side of the headstone so that after hoisting, force created by gravity acting on the headstone may be used by a workman to rotate the stone downwardly over the trailer bed where it is to be deposited for transport.
My vehicle also provides an outrigger type support which is not generally used with light trailer mounted cranes. The outrigger, however, is often necessary with my vehicle because when the vehicle is positioned on a sloping supporting surface with a heavy headstone rotated to a downward lateral position and with the crane boom extending laterally and downwardly away from the trailer structure, there may be a substantial tipping moment on the vehicle, such that without an outrigger support, the trailer might tip sideways. My particular type of outrigger support is vertically adjustable and of a symmetrical nature so that it may be used on either side of the vehicle.
My crane structure provides a mast angulated to the vertical and a boom extending substantially perpendicularly therefrom to allow greater height of the boom end than would result with the same element if the mast were vertical. The boom is adjustably mounted relative to the mast to allow selective extension. The tongue structure of my trailer has an associated vertically adjustable wheel support and downrigger to further aid stability during headstone loading or placement.
My invention resides not in any of these features per se, but rather in the synergistic combination of all of its structures that necessarily give rise to the functions flowing therefrom as herein specified and claimed.